Sensors have been used to detect acoustic waves that originate in a transmitting medium by disposing the sensors in that transmitting medium. For example, a conventional transducer may be disposed in water for detecting water borne acoustic signals. Likewise, a microphone may be disposed in air for detecting airborne acoustic signals. Such sensors have also been used to detect acoustic signals in the less and more dense medium respectively.
However, in certain applications, it may be desirable to detect in a less dense transmitting medium acoustic energy that originated in or passed through a more dense transmitting medium and traveled across an interface with a less dense transmitting medium, while compensating for energy level losses that may have occurred along the acoustic path of the acoustic energy. Further, conventional sensing systems may require that multiple dispersed transducers and/or microphones be deployed for achieving desired sensitivity. It may be difficult, uneconomical, infeasible, and time consuming to effect such deployment. Therefore, it would be desirable to employ an apparatus and method which does not necessarily require multiple sensors.
An apparatus for sensing airborne acoustic waves that is useful in practicing the present invention is described and claimed in U.S. patent application Ser. No. 06/864,481, filed May 19, 1986 and assigned to the present assignee, which is incorporated herein by reference thereto.